Reciprocating propeller.



B. D. MARKS. RBGIPROGATIN G PROPELLER. APPLICATION FILED SEPT.3. 1908.93 1 ,783. Patented Aug. 24. 1909. 2 SHEETS-SHEET 1.

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B. D. MARKS. RECIPROCATING PROPELLER.

APPLICATION FILED SEPT. 3, 1908.

\ Patented Aug. 24. 1909.

2 SHEETSSHEET 2.

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Amzw. I. mmuu cu. momma-nus. wmuum n BENNETT D. MARKS, or cIIIcAGo,ILLINOIS.

RECIPROCATING PROPELLER.

Specification of Letters Patent.

Application filed September 3, 1908. Serial No. 451,525.

To all whom-it may concern:

Be it known that I, BENNETT D. MARKS, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois,-haveinvented certain new and useful Improvements in ReciprocatingPropellers; and I do declare the following to be a full, clear, andexact description of the Invention, such as will enable others skilledin the art to-which it appertains to make and use the same.

This invention relates to new and useful improvements in reciprocatingpropellers for boats.

In constructing. propelles of this type it has beenthe common practiceto make the blades in a plurality of hinged sections so that: during thereturn stroke of the plunger the sections are permitted to fold inwardlyin order to reduce the resistance ofiered to their passage through thewater to-the greatest possible extent. This form of blade however isdecidedly objectionable because of the fact that the blade being made ina number of hinged sections the joints of the sections could notpossibly withstand the strain to which they would be subjected, as theplunger makes its thrust and consequently the parts would becomederanged or renderedunfit for service after the propeller hasbeen in usebut a short period of time.

In order to 'overcomethe above objections, I have devised a propellerwhich is cast integral or riveted tothe'plunger and have provided guideframes of the desired form whereby the blade is gradually loweredintothe water: as'the plunger makes its thrust andisraisedentirely or nearlyclear of the water as the plunger makes its return stroke;

WVith these and other objects in view, the invention consists of certainnovel features of construction, combination and arrangement of parts, aswill be more fully described: andparticularly pointed out in theappended claims Inthe accompanyingdrawings, Figure 1 is a side elevationof the stern of a boat with my improved form-of propeller applied inposition thereto; Fig. 215 a rear view of'Fig. 1 with parts broken away;F1g-. 8 1s a plan view; Fig. 4 a vertical section-taken on the planeindicated by the dotted lines H of Fig.1, looking inthe directionindicated by the arrow.

In the embodiment illustrated the numeral 1 indicates the stern of aboat of any ordinary construction and 2 the improved propelling meanswhich is arranged in the desired position with relation to the stern ofthe boat. As shown, this propelling means comprises two rigid preferablyconcavoconvex propeller blades 3 which are arranged at opposite sides ofthe stern, as shown, and are integral with or rigidly connected to therear extremities of the pivoted sections 4 of the plungers 5, the latterbeing connected with a crank shaft 6 extending transversely through thestern of the boat.

Each of the propeller blades 3 is arranged to work between a pair ofcorresponding laterally spaced guide frames 7 suitably supported in rearof the stern and at the desired height with reference to the water line.Each of these frames is of approxi mately elliptical form and isconstructed from a flat piece or bar of metal arranged in edgewiserelation with a vertical'plane and provided at opposite side edges withinwardly extending guide flanges 8 to receive suitable rollers 9journaled to opposite ends of a cross bar 10 one of which is arranged atthe rear extremity of the pivoted section of each of the plungers andbetween each pair of guide frames. By employing a construction of thiskind it will be observed that while these frames serve to guide thepropeller blades in the desired manner the plungers' are so connectedtherewith as to reduce friction to a minimum and consequently increasethe desirability of the device. These frames comprise lower portions 11which are gradually curved inwardly in the water and which extend to therear ends of the frames. The frames are then bent upwardly and forwardlyto form upper curved portions 12 of approximately semi circular form,the central portions-of which extend above the surface of the water tothe desired distance. By this construction it will be observed that asthe plunger makes its thrust its respective blade is gradually loweredinto the water until at the rear end of its pair of guide frames and isthen raised in approximately edgewise manner until out of the water andreturned to initial position.

It is to be further observed that by constructing the lower portions 11of the guide frames as indicated and described, each of the propellerblades is gradually lowered into the water as its respective plungermakes its thrust and that for this reason the impact is gradual and willnot cause severe Patented Aug. 2st, 1909.

shocks or strains to which the boat and propelling means would beotherwise subjected and which would cause the discomfiture of theassengers. It is to be further noted that by lifting the blades out ofthe water upon the return strokes of the plungers that practically noresistance if any is offered to the return of the propeller blades intoinitial or normal posit-ion to make the next thrust.

It is to be understood that while the construction of frame which 1 haveshown and described is more particularly suited for the purpose than anyotner which 1 have been able to devise at the present time, 1 do notlimit myself to this particular form of frame but claim the right to useany form or 06nstruction whereby the objects or aims in view heretoforepointed out may be accomplished. It is also evident that the crank armsof the crank shaft are arranged at 180 degrees apart in order that oneof the propeller blades will be brought into normal or initialpositionwhile the other is making its thrust. Any suitable form ofengine may be used to drive the crank shaft.

From the foregoing description, taken in connection with theaccompanying drawings, the construction and operation of the inventionwill be readily understood without requiring a more extendedexplanation.

Various changes in the form, proportion and the minor details ofconstruction may be resorted to without departing from the principle orsacrificing any of the advantages of the invention, as defined in theappended claims.

Having thus described my invention, what I claim as new is 1. Incombination with a plunger, a propeller blade rigidly attached thereto,and guide frames whereby the blade is caused to be gradually loweredinto the water during the thrust of its plunger and raised out of thesurface of the water upon the return stroke of the plunger.

2. In combination with a boat, a plunger mounted to reciprocate throughthe stern thereof, a propeller blade made in one piece rigidly connectedwith the rear extremity of the plunger, and guide frames suitablysupported in rear of the stern of the boat whereby the propeller bladeis caused to be gradually lowered into the water as the plunger makesits thrust and is raised out of the water during the return stroke ofthe plunger.

3. In combination with a boat, a plunger mounted to reciprocate throughthe stern thereof, a concavo-convex propeller blade rigidly connectedwith the rear extremity of the plunger and a pair of correspondinglaterally spaced guide frames for the rear end of the plunger wherebythe propeller blade is caused to be gradually lowered into the water asthe plunger makes its thrust and is lifted above the surface of thewater upon the return stroke of the plunger, and means for driving theplunger.

a. In combination with a boat, a plunger made in two jointed sectionsmounted to reciprocate through the stern of the boat, a propeller blademade in one piece rigidly connected with the rear extremity of the rearsection of the plunger, and means for guiding the rear extremity of therear plunger section whereby the propeller blade is caused to begradually lowered into the water as the plunger makes its thrust and israised out of the water during the return stroke of the plunger.

5. In combination with a boat, a plunger mounted to reciprocate throughthe stern of the boat a propeller blade cast in one piece rigidlyconnected with the rear extremity of the plunger, and a pair ofcorresponding laterally spaced guide frames supported in rear of thestern of the boat and for guiding the rear extremity of the plunger,said frames comprising lower gradually and inwardly curved portions andupper portions of greater curvature, the central portions of the upperportions extending above the water level, and means for driving theplunger.

6. The combination with a boat, of a plunger made in a number of jointedsections mounted to reciprocate through the stern of the boat, apropeller blade made in one piece rigidly connected with the rearextremity of the rear section of the plunger, and a pair ofcorresponding laterally spaced guide frames supported in rear of thestern of the boat and for guiding the rear extremity of the rear plungersection whereby the propeller blade is caused to be gradually loweredinto the water as the plunger makes its thrust and is raised out of thewater during the return stroke of the plunger, said frames comprisinginwardly extending guide flanges, a cross bar arranged at the rearextremity of the rear plunger section, and rollers j ournaled toopposite ends of the cross bar and adapted to bear between the guideflanges of the frames, and means for operating the plunger.

7. The combination with a boat, of a plunger mounted to reciprocatethrough the stern thereof, a propeller blade made in one piece rigidlyconnected with the rear extremity of the plunger, a pair ofcorresponding laterally spaced guide frames supported in rear of thestern of the boat for guiding the rear extremity of the plunger andwhere by the propeller blade is caused to be gradually lowered into thewater as the plunger makes its thrust and raised out of the water duringthe return stroke of the plunger, each of the frames being constructedfrom a flat piece of metal which is arranged in edgewise relation with avertical plane and is s bent at opposite side edges to form inwardly Intestimony whereof I have hereunto set extending guide flanges, a crosspiece army hand in presence of two subscribing 10 ranged at the rearextremity of the plunger Witnesses.

and extending between the guide frames,

T and rollers journaled to opposite ends of the BENL ETT MARKS crosspiece to bear between the guide flanges lVitnesses:

of the frame, With means for operating the ERNEST H. L. MUMMENHOFF,

plunger. OTTO V. HELLMRICH.

